Processing Messages

Messages are passed among different hardware and software areas. The following illustration shows paths a message can take.

Radio hardware is the first component of a Windows CE–based device to interact with a message. After the radio hardware receives a message, the message is sent through several OS levels before it reaches an application in the following way:

1. The radio hardware receives a message.

   The hardware receives all messages on monitored frequencies, whether intended for the device or not.

2. The hardware verifies that the message is for the device by reading the message address.

   If the message is not intended for the device, the message is discarded.

3. The hardware passes the message to the device driver.

   The hardware turns on the Windows CE–based device, if necessary.

4. The device driver sends the message to the router.
5. The router communicates with the device and reads the message address to determine which handler to invoke.
6. The router loads the handler and passes it the message.
7. The handler processes the message.

   The message can be processed by the default handler, or by a custom handler. You can write a handler to perform decryption, store the message data in a database, or update a calendar based on the message content.

By default, messages pass through the MSDefault message handler to PMail, a Windows CE–based mail application that synchronizes to Microsoft® Outlook® 97, a desktop information manager.